Power Steering Pressure Control Valve: Description and Operation

EPS SOLENOID

SOLENOID VALVE





A solenoid valve is provided in the gear box to control the flow of power steering oil. The solenoid valve is composed of a plunger, a releasing spring, a piston and a plunger.
The input current is varying from 0A to 1A according to the vehicle speed and steering wheel rotation speed and is controlled by Electronic Power Steering (EPS) control module.

When the ignition switch is turned on, current is sent to the solenoid valve to push up the plunger and accordingly the piston contacting the plunger is pushed up while overcoming the spring force.
As the vehicle speed increasing the current flow to the solenoid decreased pulling down the piston bottom by the releasing spring force.

When the piston is pushed up, it closes the oil passing hole, therefore the power steering oil pressure is delivered into the cylinder without any interruption. But when the hole is opened as the piston is pulling down, some of the oil coming from the rotary valve is drained into reservoir via the hole inside the rotary valve.

NOTE: When it is necessary to remove the EPS gear box, be sure to disconnect the connector to avoid damage.